Voltampermetric investigation of peculiarities of anodic processing of biomedical stainless steel AISI 304 in ethaline: temperature and additional water influence

It is shown that deep eutectic solvent Ethaline is an environmentally friendly and highly efficient medium for electropolishing of AISI 304 stainless steel that is widely used for medical products. The obtained voltammograms allow choosing optimal conditions for anodic treatment of AISI 304 steel samples in Ethaline at different temperature conditions (from 20 to 50°C) and with water additives (up to 10 %). It is established that high efficiency of Ethaline as an electrolyte for anodic treatment is primarily associated with its unique physicochemical properties: significant viscosity and, at the same time, relatively high, as for ionic liquids, electrical conductivity. The high viscosity of the Ethaline solvent causes slow diffusion of the products of anodic dissolution of steel, which achieve the formation of a viscous electrode layer and provide a high efficiency of the polishing process. It has been shown that with an increase in electrolyte temperature and water content in Ethaline the anodic dissolution rate of steel increases and this allows the use of high anode current densities for electropolishing in galvanostatic mode or lower potentials in the potentiostatic mode.